A current sensor has been proposed that measures an electric current by using a Hall effect integrated circuit (IC) made of a semiconductor material such as silicon (Si), indium arsenide (InAs), indium antimonide (InSb), or gallium arsenide (GaAs). Nowadays, a Hall effect IC, in particular, made of silicon is provided as a molded IC chip package. Specifically, as shown in FIGS. 10A-10C, a sensor chip 101 mounted on a lead frame 100 is encapsulated in a molding resin 102 so that a sensor package 103 is provided.
A current sensor disclosed, for example, in U.S. Pat. No. 7,084,617 corresponding to JP 2005-308526 and JP 2005-308527 uses the sensor package 103. As shown in FIG. 11, the conventional current sensor includes a case 110, a magnetic core 111 accommodated in the case 110, the sensor package 103 placed in a gap 112 of the magnetic core 111, a capacitor 120 for preventing noise from entering the sensor package 103, and a thermistor 121 for temperature detection.
In such a sensor package, a Hall effect element is encapsulated with molding material such as epoxy or plastic. Therefore, the Hall effect element may be subjected to stress from the molding material, in particular, thermal stress caused by a thermal strain due to a change in temperature. The stress causes a reduction in accuracy of an output signal of the Hall effect element. Accordingly, the conventional current sensor cannot accurately measure an electric current. Further, the conventional current sensor still has room for improvement in assembly. In short, the conventional current sensor is relatively difficult to assemble.